Not applicable.
Not applicable.
(1) Field of the Invention
The present invention relates to an apparatus for recording the upper airway respiratory sounds of a horse during exercise of the horse to determine whether the horse suffers from an upper airway obstruction condition. In particular, the present invention relates to an apparatus comprising a horse restraining apparatus with a support member thereon which positions a microphone forward to and between (adjacent to) the horse""s nostrils to detect respiratory sounds of the horse during exercise and which transmits the detected respiratory sounds to a recorder for analysis.
(2) Description of Related Art
Horses commonly suffer from several different upper airway obstructive diseases (conditions), including left laryngeal hemiplegia (LLH), dorsal displacement of the soft palate (DDSP), pharyngeal collapse, and entrapment of the epiglottis. Left laryngeal hemiplegia and DDSP are by far the most common causes of upper airway obstructions in horses and these conditions have an estimated prevalence of approximately 10% of horses. Left laryngeal hemiplegia is caused by a neuropathy of the left recurrent laryngeal nerve. This condition results in the paresis of the associated arytenoid cartilage. During exercise, this cartilage causes airway obstruction, respiratory noise, and exercise intolerance (Seeherman, In: Current Therapy in Equine Medicine 4. Robinson (ed), W. B. Saunders, Philadelphia, pp. 404-407 (1997)).
The cause of dorsal displacement of the soft palate is presently unknown. Experimentally, the disease is reproduced by blockade of the pharyngeal branch of the vagus nerve. Because this nerve branch runs in close proximity to the retropharyngeal lymph nodes, it is thought that in naturally occurring cases, DDSP is caused by infection of these lymph nodes and consequent damage to the nerve branch. Like in cases with LLH, DDSP causes airway obstruction, respiratory noise production and exercise intolerance in affected horses (Ducharme et al., In: Current Therapy in Equine Medicine 4. Robinson (ed), W. B. Saunders, Philadelphia, pp. 415-418 (1997)). In many cases, upper airway conditions can not be diagnosed in the resting horse as the conditions only occur during exercise. Upper airway obstructions are often associated with abnormal respiratory noise.
Respiratory sounds in exercising horses are difficult to evaluate because the trained observer is not always in an optimal location to hear the respiratory sounds. Furthermore, the respiratory sounds are obscured by extraneous noises such as hoof beats, wind noise, or sounds associated with treadmill operation. Presently, diagnostic methods are time consuming, highly technical, and expensive. The old method of diagnosing upper airway conditions in horses involves fiber optic endoscopy. In this technique, a fiber optic endoscope is inserted in the horse""s nose and observations are made. To diagnose upper airway conditions that are only apparent during exercise, the horse is exercised on a high-speed treadmill and endoscopy is performed during exercise. This method is highly technical and can only be performed in referral centers.
In human medicine, spectrogram analysis of speech is a large field of study and practical applications of this field, including speech therapy and voice recognition, are now commonplace (Kent, J. Voice 7: 97-117 (1993)). In addition, spectrogram analysis of sound has been used in many animal species, including songbirds (Lindell, Wilson Bull. 110: 368-374 (1998)) and marine mammals (Hanggi and Schusterman, Anim. Behav. 48: 1275-1283 (1994)).
Respiratory sounds of horses have been recorded using a radiostethoscope such as that disclosed by Attenburrow et al., in Equine Exerc. Physiol.xe2x80x94: 27-32 (1990) and in U.S. Pat. No. 4,218,584 to Attenburrow both of which describe a stethoscope for detecting and recording data from a horse while the horse is walking, trotting, cantering, jumping, and galloping. The invention includes a transducer, such as a microphone which is attached to the animal""s skin adjacent the windpipe. The electrical output from the transducer is transferred to a radio transmitter mounted on the animal or its harness. The radio transmitter can transmit signals a distance from the horse to allow for monitoring the horse""s breathing from a distance. While the respiratory sounds detected by the radiostethoscope placed over the trachea are analyzed using spectrogram analysis, the respiratory sounds do not directly relate to the respiratory sounds of exercising horses.
To correlate the respiratory sounds recorded by the radiostethoscope to inspiration or expiration of the exercising horse, Attenburrow in Equine Vet. J. 10: 176-179 (1978) further suspended a sub-miniature microphone just in front of one nostril. The microphone detects expiration by using the blast effect made by expired air upon the suspended microphone. The blast effect is the sound made by rushing expired air hitting the microphone which sounds much like the sound made by a strong wind hitting a microphone at an outdoor concert. Thus, the microphone is not detecting actual upper airway respiratory sounds made by the horse during respiration. Therefore, when a blast effect is detected by the microphone, the corresponding respiratory sound detected by the radiostethoscope was made during expiration. Conversely, when a blast effect is not detected by the microphone, the respiratory sound detected by the radiostethoscope was made during inspiration.
Also, of interest is U.S. Pat. No. 4,720,866 to Elias et al. which describes a method and apparatus for acquiring, analyzing, and displaying stethoscopic data using a microcomputer. The stethoscopic data come from lung sounds, not upper airway sounds as recorded in the invention described therein. The invention includes a means for providing an audio signal. The audio signal is pre-amplified and conditioned for application to a bank of fixed-center-frequency electronic filters. The output of each filter is sampled and converted to digital form. The output is then processed in a computer for analysis and display on a CRT screen or recording in a hard copy device.
U.S. Pat. No. 5,165,417 to Murphy, Jr. describes a diagnostic method and apparatus for detecting breathing abnormalities in humans to diagnose lung (not upper airway) disorders. The system includes means for receiving the sound signal from the patient, means for conditioning the sound signal to attenuate normal sounds, and means for storing a sample sound signal. The system may also include means for digitizing the sound signal, means for amplifying the sound signal, means for determining an average signal value of at least a portion of the sound signal, and means for generating a threshold value based on that average value. Further included may be means for sequentially comparing the sound waves with the predetermined time interval to identify an initial deflection wave having a duration falling within the time interval, means responsive to the means for sequentially comparing the sound waves for sequentially comparing the sound waves following the initial deflection wave to the threshold value, and means for identifying an adventitious sound occurring within the sound signal only when a plurality of consecutive sound waves including the initial deflection wave have an amplitude at least as large as the threshold value.
U.S. Pat. No. 5,737,429 to Lee describes a portable, visible, and audible stethoscope. The stethoscope includes a sound absorbing cup having a microphone and an output device. In use, the sounds from the human body are converted into electrical signals by microphone. The electrical signals are amplified in the output device and supplied to the speaker of the output device to produce an audio signal. The amplified electrical signals are also supplied to the oscilloscope to produce a graph representing the electrical signals.
Only of minimal interest is U.S. Pat. No. 5,503,141 to Kettl et al. which shows a microphone mounting structure which permits conversion of a conventional respirator into a sound amplifying respirator. The invention uses a microphone responsive to oral sounds within the respiratory mask and produces electrical signals indicative of these oral sounds. The system also includes an amplification circuit which provides output sounds representative of the oral sounds which the microphone detects within the mask.
In light of the prior art, there remains a need for an apparatus for recording the upper airway respiratory sounds of a horse during exercise which is portable and easy to use and which allows the recorded respiratory sounds to be analyzed for upper airway obstructive diseases.
The present invention provides an apparatus for recording the upper airway respiratory sounds of a horse during exercise which is portable and easy to use and which allows the recorded respiratory sounds to be analyzed for upper airway obstructive diseases either after exercise or in real time.
In particular, the present invention provides an apparatus for recording respiratory sounds of an exercising horse which comprises (a) a microphone with a head which detects respiratory sounds at close proximity; (b) a horse restraining apparatus comprising a nose-band and a cheek-piece with a top for going behind and around the ears of the horse both mountable on the head of the horse wherein the horse restraining apparatus includes a support means for the microphone mounted on the nose-band of the horse restraining apparatus wherein the support means allows the head of the microphone to be positioned between nostrils of the horse without touching the horse so that the respiratory sounds at close proximity to the nostrils of the horse are detected; and (c) a recording means for recording the respiratory sounds from the microphone at close proximity to the nostrils of the horse wherein the recording means squelches other sounds at a distance from the nostrils.
In a further embodiment of the apparatus, a wire for transmitting the respiratory sounds detected by the microphone to the recording means extends from the microphone to the recording means along a path which is parallel to the support means mounted on the nose-band of the horse restraining apparatus and is parallel to the nose-band and the cheek-piece to the top of the cheek-piece and which extends from the top piece to the recording means.
In a further embodiment of the apparatus, the support means is a tube defined by at least one wall forming the tube in which the wire for transmitting the respiratory sounds extends therethrough.
In a further still embodiment of the apparatus, the microphone is unidirectional.
In a further still embodiment of the apparatus, the recording means has a compression circuit which allows for a constant recording level of the sounds at close proximity to the nostrils of the horse.
In a further still embodiment of the apparatus, the microphone includes a wireless transmitter for transmitting the respiratory sounds to a wireless receiver in the recording means.
In a further still embodiment of the apparatus, the microphone includes a wireless transmitter for transmitting the respiratory sounds to a wireless receiver in a computer for analyzing the respiratory sounds in real time.
The present invention further provides a method for recording and analyzing respiratory sounds of an exercising horse to detect an airway condition which comprises (a) providing an apparatus for analyzing respiratory sounds of an exercising horse which comprises (1) a microphone with a head which detects respiratory sounds at close proximity; (2) a horse restraining apparatus comprising a nose-band and a cheek-piece with a top for going behind and around the ears of the horse both mountable on the head of the horse wherein the horse restraining apparatus includes a support means for the microphone mounted on the nose-band of the horse restraining apparatus wherein the support means allows the head of the microphone to be positioned between nostrils of the horse without touching the horse so that the respiratory sounds at close proximity to the nostrils of the horse are detected; and (3) a recording means for recording the respiratory sounds from the microphone at close proximity to the nostrils of the horse and squelches other sounds at a distance from the nostrils; (b) mounting the head of the microphone adjacent to the nostrils of the horse; (c) recording the respiratory sounds detected by the head of the microphone with the recording means; and (d) analyzing the respiratory sounds recorded on the recording means to detect the condition.
In a further embodiment of the method, a wire for transmitting the respiratory sounds detected by the microphone to the recording means extends from the microphone to the recording means along a path which is parallel to the support means mounted on the nose-band of the horse restraining apparatus and is parallel to the nose-band and the cheek-piece to the top of the cheek-piece and which extends from the top piece to the recording means.
In a further still embodiment of the method, the support means is a tube defined by at least one wall forming the tube in which the wire for transmitting the respiratory sounds extends therethrough.
In a further still embodiment of the method, the microphone includes a wireless transmitter for transmitting the respiratory sounds to a wireless receiver in the recording means.
In a further still embodiment of the method, the microphone includes a wireless transmitter for transmitting the respiratory sounds to a wireless receiver in a computer for analyzing the respiratory sounds in real time.
In a further still embodiment of the method, the analysis is for laryngeal hemiplegia and dorsal displacement of the soft palate.
In a further still embodiment of the method, a computer program produces a graph of the respiratory sounds for analyzing in step (d).
The object of the present invention is to provide an easy and inexpensive method and apparatus for diagnosing upper airway obstruction conditions in exercising horses.
That and other objects of the present invention will become increasingly apparent with reference to the following drawings and examples of embodiments which satisfy the objects of the present invention.